Takis Posted July 11, 2018 Share Posted July 11, 2018 I recently bought a 1968 GS with a 455 rebuilt engine in it... I have the original red line and original rally rims on it. It looks good, but I have always like chrome rims with bigger tires on a muscle car. What type/size rim/ etc. would you recommend? I would appreciate any input... I do not know if they are 15: or 14" rims either.. and i think the lug nuts are 7/16" from investigating a little on the Internet. I would appreciate confirmation on those params too... Thank you very much for any help. Takis Link to comment Share on other sites More sharing options...
Matt Harwood Posted July 11, 2018 Share Posted July 11, 2018 I think anything bigger than 17s looks goofy on a vintage muscle car. You need some tire sidewall or else it just looks like it's sitting on railroad wheels. We recently did this '69 GS that came with drag race 15-inch wheels on it. The wheels we used were 17x7 front and 17x8 rear with modestly-sized tires. Too much tire causes more problems. These fit and didn't rub, although getting them out of the rear wheel wells required removing the rear shocks to get enough droop to put them on. I think they were 245/40/17 front and 275/40/17 rear. Same fittment as a Chevelle so you should be able to find something that works. I have forgotten the bolt circle, I think it's 5x4.5 but you should measure to be certain. Good luck! 2 Link to comment Share on other sites More sharing options...
Takis Posted July 11, 2018 Author Share Posted July 11, 2018 Matt.. Thanks for the quick reply... I like the look for the 2nd picture... I know I have 14" rims currently.... I am assuming if I place 15: rims.. they should still fit? I am ignarant to altering sizes on cars.. never customized tires before... I am assuming the bolt circle just changes... So, the above is 15" rims withi 17x7 front and 17x8 rear tires ? Thanks Link to comment Share on other sites More sharing options...
Matt Harwood Posted July 11, 2018 Share Posted July 11, 2018 (edited) No, those are 17-inch wheels and tires--the last digit in the tire size is the wheel diameter on which those tires fit. A 17x8 wheel means it is 17 inches in diameter and 8 inches wide. But there are other factors like offset, backspacing, and bolt circle that have a big impact on how they fit and whether they will rub. It can be confusing and I recall that I researched that particular setup for two or three days before buying the wheels/tires. Do your homework first! If you want 15s, I might suggest finding a set of Buick Road Wheels, which will bolt right on and look right. They're available in both 14- and 15-inch sizes and should have a bolt circle that fits your car properly. I think Buick Road Wheels are the best-looking factory wheels of the period and with a set of redline radials, any car would look great. I'd recommend doing some browsing around to see what wheels look good and how they fit, as well as doing some research on wheel bolt circles, offset, backspacing, and tire sizing. That will give you the tools to figure out if what you are considering purchasing will actually fit the car. Remember, once you put them on the car, most wheel and tire sellers will not take them back. Here's a '68 GS convertible with what appear to be 15-inch Buick Road Wheels and tires that likely measure 215/60/15 (maybe 225/60/15): Edited July 11, 2018 by Matt Harwood (see edit history) Link to comment Share on other sites More sharing options...
Takis Posted July 11, 2018 Author Share Posted July 11, 2018 THanks.. this is what I am doing my homework to understand everything... I got the tire measurement params down... I am positive I have 14" rims that look almost exactly (not in size if they are 15: rims) like the picture you placed in the blue convertable - I also have the redline too... still would like to upgrade to bigger rims and tires... I will take a picture soon and place here for anyone in the future that may need to do this... Now to investigate offset, backspacing, and bolt circle... Link to comment Share on other sites More sharing options...
JohnD1956 Posted July 12, 2018 Share Posted July 12, 2018 That half open wheel welt in the rear is a real pain. My 69 GS, which has the same opening, was a big problem when I had a blow out away from home on some 235-60 series ties with 14" Buick Regal road wheels. Had to use the bumper jack almost to the top, and then a portable floor jack under the axle to manipulate the rim and tire around the brake drum and the small opening. That was not fun! Freaking thing almost fell over off the bumper jack. While the fat tires looked great, I do not miss them at all and now have the 225-70 series BF Goodrich radials on the original 14" rims. These go on and off with no issue. 1 Link to comment Share on other sites More sharing options...
RivNut Posted July 12, 2018 Share Posted July 12, 2018 (edited) The info on the tire itself will tell you the size of the wheel. The intermediate GM cars have a 4.75" bolt circle. Those 'two piece' Buick rally wheels were usually 14". Original tires I the late 60s would have been something like G60-15. Those were bias ply tires On modern radial tires, the first number on a tire tells you the width in millimeters. The second number is the percentage of the first number, which gives you the height. The last number tells you, in inches, the bead diameter of the wheel - not the outside diameter. So a 235/60R15 tire would be 235 mm wide, the height would be 60% of 235 mm, the R stands for Radial, and the 15 would be the measurement of the diameter of the wheel's bead in inches. This is a picture of what I referred to as a 14" 'two piece' wheel off an intermediate sized cars. You'll notice a separate rim and wheel center. Like the ones on the car in the picture. This is a picture of a 15" rally wheel off a full sized car. You'll notice that there is no separate center and rim. These wheels have a 5" bolt circle. They do not interchange. Edited July 12, 2018 by RivNut (see edit history) 1 Link to comment Share on other sites More sharing options...
Takis Posted July 13, 2018 Author Share Posted July 13, 2018 Thanks for the feedback... A little more info... THe current wheels I have or on the 15" rally types.. the tire size is 225/60R/15... I currently went ot a Firestone dealer to figure out what tires and rims to get. I did this so I do not order something incorrect and cannot return. I will let you all know what happens as soon as I get things installed. The info that you all gave was great. Thanks Link to comment Share on other sites More sharing options...
NTX5467 Posted July 15, 2018 Share Posted July 15, 2018 AND . . . to make matters worse, there's also "back spacing" in the mix, too! The 15x7 '70s Camaro factory Z/28 15x7 steel wheels are supposed to have a 4.25" backspacing. I suspect the other similar GM wheels are about the same for a 7" wide rim. Some wheels are more like 4" backspacing on a 7" wide rim, which puts the tire closer to the outside edge of the car. With "the look" can come some inconveniences, as noted. Usually best to have something that goes off and on easily, or have the local tow service's number in your cell phone directory. There are some 17" tires that have very similar "revs/mile" specs as the OEM 15" tires of the later '60s and such. This keeps the speedometer more in correct calibration. This might be a plus for the 17" wheels in the future, by observation. Depending upon the tire's tread design, the wider treads can be more prone to hydroplaning in heavy rain, than a narrower tread width. Best to do "dough nuts" on dry parking lot pavement than on a wet freeway! Many side issues with the "something bigger" orientation. Sometimes, discretion is the better part of valor. NTX5467 Link to comment Share on other sites More sharing options...
Takis Posted July 16, 2018 Author Share Posted July 16, 2018 All right.. I will give you all a status.. I was going to wait till the job was done with before and after pictures, but I will give you a quick update. I went to my local Firestone tire dealer that I have been going for the last 15 years... Thye are good people and they gave me a good price... but more importantly, we worked together to come up with this scenario... These ar the rims I am getting... 106C-78610 17X8, OE Performance, 106C These are the front tire's params... 245/45ZR17XL - thus 9.6: width in front... These are the rear wheel params... 255/45ZR17 - thus 10" width in back Tires or Nitto - Nitto, NT555 G2 (summer - only time I will be driving this car anyway - live in CLE, OH)) This is similar to the above specs someone mentioned.. but we are hoping no extra work will be needed to install the rear tires, including bending inner lip and/or having to take off air shocks to install... I will follow up once done... moreover, as it was mentioned above, these 17" rims will not affect odometer and mph readings, supposedly... They stated 7-10 business days to ship... so, I will get back with everyone once I have a chance to take pictures and ride with the new set of tires for a day or so. Thanks for everyone's input... Taki Link to comment Share on other sites More sharing options...
Takis Posted July 16, 2018 Author Share Posted July 16, 2018 I placed air shocks already that go up 140psi to give the car a little angle from the back, but since they are peak, I am losing air, thus the profile goes back to close to the original. Are there any air shocks that may fit the 68 GS body (Type-A) for the psi to be higher, so I can get the profile.. especially with new rims and wheels. Thanks Link to comment Share on other sites More sharing options...
Takis Posted July 24, 2018 Author Share Posted July 24, 2018 Here are a couple pictures.. sorry not the best pictures... Link to comment Share on other sites More sharing options...
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